To earn points under the Environmentally Preferable Products (EPP) credit in the LEED for Homes 2008 rating system, specific pathways were available for different product categories. For insulation, the requirement was that a minimum of 90%, measured by area, of all insulation installed in the home must be reclaimed or salvaged material. This high threshold ensured that the project made a significant commitment to reusing materials and diverting waste from landfills for this major building assembly, thereby earning credit toward certification.

A. 70%: This percentage is below the minimum threshold required by the LEED for Homes 2008 standard for the salvaged insulation pathway.

B. 80%: This is an incorrect value; the standard explicitly sets the minimum requirement higher to ensure a significant environmental benefit.

D. 100%: While using 100% salvaged insulation would meet the requirement, the minimum threshold to earn the credit point was 90%.

1. U.S. Green Building Council. (2008). LEED for Homes Rating System. Washington, DC: U.S. Green Building Council. Page 81, MR Credit 2.2: Environmentally Preferable Products, Insulation pathway.

2. Kibert, C. J. (2016). Sustainable Construction: Green Building Design and Delivery (4th ed.). Wiley. Chapter 11, "Assessing Building Performance," discusses the evolution and specific credit requirements of LEED rating systems, including material reuse thresholds from earlier versions like LEED 2008. (Note: This text is widely used in university curricula on sustainable construction).